The pink cube, which is 78 km high (49 miles) is the actual volume of our 'carbon budget': 900 billion tonnes of CO2. The shapes to the right show the emissions from proven reserves listed in Global Energy Outlook 2012. There are high resolution versions of this image on Flickr.

MPs in the UK will vote on the Energy Bill on Tuesday (4 June 2013). The Bill as it currently stands has no targets for switching from fossil fuels beyond 2020, which according to Danielle Lane of DONG Energy UK, will have a severe impact on investor confidence in the renewable's sector (see The Energy Bill, work to be done).

Clean energy is not a 'nice to have if we could afford it' policy. It's not like a policy to improve air quality, where there may be scope to find a compromise between health and economic impacts. As well as threatening the planet, delaying de-carbonisation will leave the UK's economy stranded. Any good a politician may do in his or her political career will be dwarfed by the damage they will cause by failing to act now. MPs who want to secure their legacy should think very carefully about how they vote on this crucial Bill.

As the diagram shows, we have a tiny carbon budget to work with. Carbon Tracker, in collaboration with the Grantham Research Institute for Climate Change and the Environment at the London School of Economics and Political Science, estimate that our available ‘carbon budget’ is 900 Gt CO2for an 80% probability to stay below 2°C and 1075 Gt CO2 for a 50% probability. (See: Unburnable carbon 2013: Wasted capital and stranded assets.)